Various porous particles are developed and a potential of a drug delivery system (DDS) as a drug carrier is studied (PTLs 1, 2, and 3). In PTL 1, a porous material excellent in releasing property of a non-steroidal anti-inflammatory compound is provided. In PTL 2, a porous material that functions as a carrier of a drug and drug-containing nanoparticles is disclosed and improvement in oral absorbability of the drug is achieved by improving dissolution. In a case where the porous material is used as a carrier for these low molecule drugs, the objective thereof is dissolution assistance. In PTL 3, porous particles are used as a drug carrier in gene therapy. Stabilization of gene drug and effective intracellular delivery are achieved. The porous particles composed mainly of an inorganic material and/or a carbon material are hard and do not decompose rapidly in a living body, and if the porous particles are present for a long period of time, there is a possibility of adversely affecting the living body. Porous particles using a polymer material are developed (PTLs 4 and 5), but it takes time to decompose the porous particles and impurities such as monomers remain, so that there is a possibility that biological safety problems occur. PTL 4 relates to water-insoluble porous particles of a biocompatible substance and a production method thereof. PTL 5 relates to porous polymer particles on which charged molecules are immobilized and a production method thereof.
NPL 1 is a review article on medical applications of porous silica particles. The use of silica related materials as a porous material is described.
NPL 2 is a review article on preparation of a porous material using a polymer compound. NPL 2 specializes in using polymer compounds.
NPL 3 is a document which confirmed that indomethacin was encapsulated in porous silica, the dissolution of the drug was improved, and the oral absorbability in an animal was improved. The Porous particles are used as a material for improving dissolution.
NPL 4 is a review article on shape control of organic material particles using spray drying. A porous material with an organic compound is disclosed. A method of forming porous particles by removing spray dried particles containing a template by heating or dissolving is disclosed. The pore size is mainly submicron, which is very large, is disclosed.
NPL 5 is a review article on a method of preparing microparticles for pulmonary administration of pharmaceutical products. A method for preparing porous particles by an organic material is disclosed. It is disclosed that porous particles can be obtained by adding a material that vaporizes during spray drying. The pore size is mainly submicron, which is very large, is disclosed.
NPL 6 discloses that a porous material directed to use in regenerative medicine can be prepared by freeze-drying.